The present invention arises from requirements encountered during magnetron sputter coating of substrates. However, it was found that the solution resulting from the present invention can be generally employed for substrate surfaces treated by vacuum treatment processes.
Definition
Within the scope of the present application by vacuum treatment process and, correspondingly, by its effect on a substrate, is understood a process                a) in which with plasma enhancement material is removed from the substrate surface, as in reactive or non-reactive plasma etching,        b) in which material on the substrate surface is modified, as in reactive plasma-enhanced secondary treatment, for example afteroxidation of the substrate surface material,        c) in which material is applied onto the substrate surface, be this reactively or non-reactively or by means of plasma-enhanced CVD. If therein material is released from the solid phase into the process atmosphere and, after reaction with gas, is deposited on the substrate surface, a process under consideration is exclusively understood as one in which the release of said material from the solid phase takes place at a material source at which the solid phase of only a single material is present.        
If two or more sources are present with different materials in the solid phase for release into the process atmosphere, each of the release processes and, correspondingly the coating processes of the, or with the, individual materials is considered as a vacuum treatment process by itself. In such a case two and more treatment processes are carried out simultaneously.
In magnetron sputter coated substrate surfaces it is today already possible to attain good coating thickness distribution, if viewing this distribution takes place in cutting planes perpendicular to the surface of the substrate. However, if the coating thickness distributions resulting in said cutting planes, in which each is assessed as good to very good, are compared among themselves—thus from cutting plane to cutting plane—then, if they are considered two-dimensionally as a coating thickness distribution over the surface, the distribution is found to be unsatisfactory.
If, for example, on sputter-coated circular disk-shaped substrates the layer thickness is received along the substrate periphery, a distribution results which for many application purposes is entirely unsatisfactory.